Conventionally, process cartridges such as one disclosed in Japanese Unexamined Patent Publication No. HEI 9-6214 are known as developer containers for containing developer. The process cartridge includes a photoconductive member and a developing device. In the developing device, a partition wall separating a toner container containing toner and a development chamber is formed with an opening for toner supply. A toner sealing member is thermally welded over this opening. In order to begin use of the process cartridge, the toner sealing member is wound up by a winder mechanism to open the opening.
The winder mechanism includes an interrupting mechanism operable to interrupt transmission of a driving force to a winder member upon completion of the opening, i.e. when the toner sealing member is wound up around the winder member. A change in the magnitude relationship between a winding torque of peeling the toner sealing member and a predetermined biasing force of a spring member causes disengagement of a drive transmission gear, consequently interrupting the driving force transmission.